There exists many attempts in the prior art to remotely uniquely identify product items and to collect, collate and process such product identifiers so as to provide a centralized reporting and tracking capability over such product items when widely distributed.
For example, applicant is aware of U.S. Pat. No. 5,289,372 which issued to Guthrie et al on Feb. 22, 1994 for a Global Equipment Tracking System. Guthrie teaches an attempt to keep track of the changing configurations of individual computers tied to a central data base by means of modem communication. The product items being tracked are in fact the various hardware units which configure each computer. Each hardware unit has associated therewith a sensor. Each sensor is hardwired to a collector for each computer. The collector for each computer transmits its configuration information, based on input from the sensors, when interrogated via modem communication by a host computer. The problems associated with tracking individual product items which are being quickly distributed along distribution paths within a distribution web are not addressed.
Applicant is also aware of U.S. Pat. No. 4,636,950 which issued Jan. 13, 1987 to Caswell et al for an Inventory Management System Using Transponders Associated With Specific Products. Caswell discloses the use of radio frequency transponders on relatively expensive to purchase items which may spend relatively long periods of time at a dealer's location where, for example, motorcycles or automobiles may be sold. Caswell teaches the use of short range radio transponders built into each product so as to uniquely identify each product, upon interrogation by a fixed interrogation transponder at the dealer's location, with a unique identification code preinstalled into random access memory in the product transponder. A host or central computer system, via modern communication to computers at the dealer's locations, relay commands that trigger the dealer's interrogator transceivers to interrogate the transponder equipped products in the dealer's inventory using, sequentially, each of the serial numbers of the products which have been shipped to that dealer and which are not known to the host computer system to have left the dealer's inventory. It is taught that in, for example, sufficiently large showroom areas, to use a multiplicity of interrogatory transceivers. It is also taught that interrogations by the interrogator transceivers are repeated at least in cases where unusual responses are encountered, to observe consistency and permit overcoming a limited amount of noise interference. It is further taught that an interrogator transceiver might be placed with its antenna field covering an exit or entrance into a merchandise storage area so as to check that properly scheduled product units are exiting or entering. The inherent limitations in such “choke-point” interrogations are in part recognized in that Caswell states that in cases such as factory or warehouse exits where it is desired to monitor a large number of units in limited interrogation time, the use of ambiguous codes transmitted by the interrogating transceiver or the use of different operating frequencies may allow for unique identification of different product items or groups of such items such as brands or types of merchandise. The solution to the problem of the choke-point interrogation such as taught in the present invention is not suggested.
Applicant is also aware of U.S. Pat. No. 5,671,362 which issued to Cowe et al on Sep. 23, 1997 for Materials Monitoring Systems, Materials Management Systems And Related Methods. Cowe teaches the inventory tracking of items that will fit on a sensor equipped shelf. The shelf sensors may detect items by the presence of the item's weight upon the shelf. It is also taught that each product packaging will include a label which is machine readable, the label being, for example, bar code, magnetic, holographic or radio-emitting so as to provide for identification and tracking of the product. It is also taught that the sensing systems may include three dimensional movement detection systems employing infrared, ultrasound, optical, radio wave or otherwise signaling techniques accompanied by suitable processing such as ranging or imaging to determine the inventory status of stored items on the shelf. The problems actually associated with unique identification and tracking using radio frequency transponders, which it is one of the objects of the present invention to address, are not taught nor suggested, and nor are the solutions.
Applicant is also aware of U.S. Pat. No. 5,266,925 which issued Nov. 30, 1993 to Vercellotti et al for an Electronic Identification Tag Interrogation Method. Vercellotti discloses a method of retrieving unique tag identification signals when multiple signals are received upon electronic interrogation at a portal. Upon receipt of more than one reply by the interrogator at the portal, the interrogation address is bisected and retransmitted, and subsequently again bisected and retransmitted until a single response is isolated. The method is then repeated to isolate and identify the remaining tags. The handling of choke-point interrogation and multiple replies such as employed in the present invention is neither taught nor suggested.
With respect to the use of environmental sensors, such as temperature sensors cooperating with RFID tags, in the prior art it is known to use temperature loggers not associated with real time communication of the data to remote interrogators. Prior art temperature loggers are electronic or mechanical devices that record temperature over a time period. Temperature loggers used in prior art mobile applications do not have communications links to aid in automation and therefore require significant human intervention. That is, in the prior art, it has been impossible to fully automate the temperature logging process. The data contained in a temperature logger needs human intervention to extract its log. Sometimes, depending on the design of the logger, the logger needs to be sent away to be processed, the results being returned in electronic or paper format. Because of the human intervention, monitoring, as a real-time event, and automatic log retrieval and analysis are not possible.